Can you please explain the in-center dialysis procedure?

It is hemodialysis. Patient arrives and gets to sit on his chair after he is weighed. His access is established using needles making 2 I.V. Lines or via his line. Then the machine is set and the blood flows through one I.V. Line into the filter in the machine and returns, purified, via the other I.V. Line to the patient. The blood keeps flowing in this manner continuously for 3-4 hrs then needles are disconnected.
Dialysis. You usually sit in a chair that is pretty comfortable. A technician checks your pulse, temp, and bp. You are attached to a dialysis machine using two needles. You are treated for about 4 hours. Your blood is returned to you through the needles. The needles are taken out and modest pressure is applied over the needle holes. You wait for awhile and then go home.